1. Field of the Invention
This invention relates to the field of ultrasonic analysis of bone tissue in humans, and more particularly to an apparatus using novel techniques for reproducibly measuring certain properties of the heel bone or os calcis using transmission and reflection of ultrasonic energy.
2. Description of Related Art
Certain known techniques for measuring properties of the heel bone or os calcis have required that the foot is held between a pair of ultrasonic transducers in a jig or clamp while the foot and the ultrasonic transducers are immersed in a water bath to couple the ultrasonic energy between the transducers and the foot. These immersing procedures reduce interference with the coupling of ultrasonic energy which is caused by air or other gas present between the transducer and the object to be tested. However, the techniques are relatively time consuming and can be inconvenient.
Other previous designs of ultrasonic bone testing apparatus include a support behind the leg in the calf muscle area. The use of a footrest allows some tolerance for the positioning of the foot. However, the approach has the disadvantage that the footrest does not facilitate consistent measurement because the size and location of calf muscles can vary greatly. In addition, the patient's calf muscle tends to be flaccid while the patient is sitting, and therefore does not provide a fixed reference surface even for the same person during subsequent measurements.